Polymeric films tend to transmit moisture (e.g., water vapor), which can be undesirable if the transmission of moisture is detrimental to components that are secured to or subsequently formed on the film. As one example, organic electroluminescent devices may suffer reduced output or premature failure when exposed to moisture. Techniques have been developed to encapsulate and prolong the life of such devices, which may be sufficient if the device is formed on a glass substrate that is impermeable to moisture. Increasingly, however, it is desirable to form such devices on a polymeric film, but such films tend to inherently transmit moisture. A protected polymeric film that exhibited low permeability to moisture would be especially useful, but despite intense industrial effort to develop such a film, only limited success has been attained so far.